Living matter is defined by more than the chemistry that governs the matter. Indeed, if one were to take the components of living matter (e.g., proteins, fats, sugars, nucleic acids, ions, etc.) and combine those components ex vivo, one would not reconstitute or otherwise create life. In fact, these components would generally tend to decompose into more base elements due to entropy. In that regard, living matter may be distinguished from the sum of its components by its ability to acquire energy and to employ that energy in defeating entropy. Specifically, cells are capable of creating individual or discrete compartments in which differing or unique chemical environments (e.g., ionic, pH, etc.) are maintained. These successive compartments establish and maintain specialized environments in which ordinarily unfavorable chemical reactions become permissible. Living matter “defeats” entropy most often by moving chemical reactions from compartment to compartment, using the individual compartments to create order out of chaos. Thus, life is distinguished from inorganic matter in that living matter is capable of employing energy to construct order (such as proteins) from otherwise disorganized building blocks (such as amino acids). In practice, an analysis of cell dynamics is essential in developing an understanding of cell biology.
Various methodologies have been developed to study cell dynamics. One of the more widely studied developments in this field involves the discovery of a protein from Aequorea victoria, a jellyfish that populates the Puget Sound region of Washington State. This protein is one of many found to fluoresce when exposed to deep blue light; this particular protein from Aequorea victoria is known as Green Fluorescent Protein (GFP) because green light (e.g., in a range generally centered around a wavelength of approximately 510 nm) is emitted when the protein is illuminated with deep blue light (e.g., in a range generally centered around a wavelength of approximately 410 nm).
As is generally understood in the art, GFP has a characteristic known as “self-assembly,” i.e., it will self-assemble into a fluorescent form, even when expressed as protein chimera with mammalian proteins in mammalian cells. This means that new proteins can be created where the GFP protein is merely a continuation of a native protein. This new protein complex (the chimera) is fluorescent and permits the visualization of the native protein in its native environment.
Since the discovery of GFP, molecular biologists have succeeded in creating variants of the GFP protein, further optimizing its application in the study of mammalian cells. One such variant of GFP includes a modification of the absorption properties of the protein so that it is optimally excited by light having a wavelength of approximately 488 nm. Another notable modification to GFP involved creation of a variant that is only weakly fluorescent until it is activated by exposure to deep blue light having a wavelength of around 413 nm; once activated at this wavelength, the GFP variant becomes about one hundred times more fluorescent (488 nm excitation, 510 nm emission) than it was prior to activation.
Conventional technology is deficient at least to the extent that a system and method have yet to be designed that are operative in concert with, and take optimum advantage of, this photoactivated GFP (PA-GFP).